The Neptune was dreamt up by production designer Peter Lamont and was constructed from drawings by draughtsman Jim Morahan. Lamont said, “I wanted it to look as authentic as possible, and this meant including a clear, dome-shaped nose for the front of the craft. A company in the South of France supplied just what we needed, molded out of plexiglass.” Two submarines were built measuring twenty-three feet in length and eight feet in width. Lamont hired the marine engineers Perry Oceanographics in Florida, who had transformed one of the Lotus Esprit shells into a fully operational underwater craft for The Spy Who Loved Me, to fit the first Neptune with an engine to give the impression that it was a fully working submarine. The second was a lightweight version used to shoot the scenes where the Neptune is winched out of the water and back aboard The Triana. The interior shots with Roger Moore and Carole Bouquet were filmed on a set built at Pinewood Studios. Visual Effects Supervisor, Derek Meddings also contributed to the sequence capturing model shots in the water tank on the 007 Stage. 

 “Like The Spy Who Loved Me, the aquatic scenes were shot in the crystal-clear waters in the Bahamas. The action was directed by respected underwater cinematographer, Al Giddings who had impressed the Bond team with his work on The Deep (1977). The veteran recalled that the Neptune was a wet submarine (meaning it does not provide a dry environment for its occupants and is instead flooded with water) but the story dictated it was a fully operational sealed dry sub. Giddings had to rely on inventive film illusions. As the divers inside at the controls passed the camera, they removed their scuba gear, “When they saw the red lights come on my underwater cameras, they spat out their regulators, made the maneuver passed camera and held their breath, (so we didn’t see any bubbles).”